title: ["Slowing" right bundle-branch block in reciprocating tachycardia from a latent right lateral Kent bundle].
abstract: The authors report the case of a 56 year old man with paroxysmal reciprocating tachycardia. The participation of a right lateral Kent bundle, latent in sinus rhythm and with retrograde atrioventricular conduction during tachycardia was proved by : 1) the slowing of the tachycardia rhythm and lengthening of the ventriculo-atrial conduction time by 50 ms during right bundle branch block ; 2) atrial mapping during tachycardia showing right lateral atrial pre excitation ; 3) the spontaneous termination of some attacks after a blocked Hisian depolarisation. Analysis of the mechanisms of spontaneous termination of tachycardia showed a block in the accessory pathway in 80% of cases, leading to the successful use of Amiodarone. The particular electrophysiological mechanism of functional bundle branch block makes it the most reliable positive diagnostic criterion in reciprocating tachycardia. A review of previously reported series shows participation of right lateral and septal accessory pathways to be uncommon during reciprocating tachycardia. Functional bundle branch block does not necessarily lengthen the ventriculo-atrial interval with septal accessory pathways. Left lateral Kent bundles are much more common. These points are analysed together with the mechanism of functional bundle branch block in the discussion.
mesh_terms: D002037:Bundle-Branch Block / Q000209:etiology* / Q000503:physiopathology; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013614:Tachycardia, Paroxysmal / Q000150:complications* / Q000503:physiopathology
vernacular_title: Bloc de branche droit "ralentisseur" dans une tachycardia réciproque empruntant un faisceau de Kent latéral droit inapparent.